1. Field of the Invention
This invention relates to systems and methods for inputting characters using keyboards.
This application is based on Patent Application No. Hei 10-282359 and No. Hei 10-326555 both filed in Japan, the contents of which are incorporated herein by reference.
2. Description of the Related Art
Conventionally, keyboards are widely used to input character information into electronic digital devices. As the representative of the keyboards, personal computers normally use the so-called "QWERTY" keyboards. The QWERTY keyboard has a relatively large number of keys. Recently, however, it is demanded to cope with downsizing of "portable" (or "handy") digital devices. In order to do so, it is necessary to downsize input devices such as keyboards by reducing a number of keys. In case of portable telephones (or cellular phones), for example, ten keypads originally used for inputting telephone numbers are used to input twenty-six alphabetic letters.
For instance, Japanese Patent Application, First Publication No. Hei 6-102979 discloses a keyboard suited to the downsizing of the digital devices described above.
Now, such a keyboard will be described with reference to FIG. 14.
FIG. 14 is a schematic illustration showing an arrangement of keys of a one-hand keyboard 801. The one-hand keyboard 801 contains fifteen main keys 802, five control keys 803, ten function keys 804 and four cursor keys 805 as well as a kana mode key 806 (where "kana" denotes the Japanese syllabary), a symbol mode key 807, a numeral mode key 808 and a shift key 809. Incidentally, a lamp is turned on when each of the keys 806, 807, 808 and 809 is pressed.
The main keys 802 are used for inputting data into some digital device equipped with the one-hand keyboard 801. The main keys 802 are arranged in a matrix consisting of three rows and five columns. In the main keys 802, five main keys arranged in a middle row are respectively provided for five characters corresponding to five vowels in Japanese, i.e., "A", "I", "U", "E" and "O", while main keys arranged in other rows are respectively provided for ten characters, which correspond to unvoiced consonants and voiced consonants. Four characters corresponding to the voiced consonants are input using a shift function being associated with the corresponding unvoiced consonants. Incidentally, remaining alphabetic characters are input using the shift function. Each voiced consonant can be input by pressing a key of the corresponding unvoiced consonant twice. Thus, the one-hand keyboard 801 actualizes operations to input Japanese characters using roman letters and operations to input alphanumeric characters with high performance.
As shown in FIG. 14, a layout of the keys of the one-hand keyboard 801 is designed such that the control keys 803, function keys 804, cursor keys 805, kana mode key 806, symbol mode key 807, numeral mode key 808 and shift key 809 are arranged in surrounding areas of the main keys 802. Thus, it is possible to actualize functions of the normal keyboard used for data input on the one-hand keyboard 801.
Japanese Patent Application, First Publication No. Hei 5-216575 discloses a keyboard in which an arrangement of consonant keys used for inputting consonant characters is separated from an arrangement of vowel keys for inputting vowel characters in left-right directions while at least two thumb shift keys (i.e., left thumb shift key and right thumb shift key) are arranged at left and right base portions respectively. Using the thumb shift keys, four shift patterns are provided for inputting a consonant character by pressing the corresponding consonant key, as follows:
i) The consonant key being pressed is subjected to shift using the left thumb shift key. PA1 ii) The consonant key is subjected to shift using the right thumb shift key. PA1 iii) The consonant key is subjected to "double" shift by simultaneous depression of the left and right thumb shift keys. PA1 iv) The consonant key is not subjected to shift at all.
Similarly, four shift patterns are provided for inputting a vowel character by pressing the corresponding vowel key. So, there are provided sixteen combinations of shift patters in total due to combinations of the four shift patterns of the consonant key and four shift patterns of the vowel key. Within such sixteen combinations of shift patterns, five combinations of shift patterns are selected and combined with three keys, which correspond to three vowel keys being arranged in three rows respectively. Thus, it is possible to produce fifteen combinations between the shift patterns and keys. Then, a large part of fourteen consonant characters used in the Japanese language and a symbol showing non-existence of the consonant are assigned to the fifteen combinations respectively. Such assignment is commonly accompanied with each vowel key in the same row so as to actualize a complex key. Using such a complex key, two syllables of a Japanese word are simultaneously input. That is, pressing the complex key allows simultaneous input of a vowel character corresponding to an odd-numbered syllable and a consonant character corresponding to a next even-numbed syllable in the Japanese word being input. Thus, it is possible to omit pressing the key for inputting the consonant character corresponding to the even-numbered syllable of the Japanese word.
The aforementioned one-hand keyboard suffers from a problem as follows:
In order to input a voiced consonant character using the one-hand keyboard, it is necessary to repeatedly press the corresponding key twice. So, it is impossible to distinguish between operations to simply input the same character twice and operations to input the voiced consonant character by repeatedly pressing the key twice. Because, the one-hand keyboard lacks a specific function to distinguish between those operations. Another problem is that the one-hand keyboard is not so good in performability. Because, the vowel key adjoins the consonant key.
The aforementioned keyboard using the thumb shift keys suffers from a problem as follows:
It is impossible to produce English documents using such keyboard.
Because, the keyboard does not have keys for inputting letters (e.g., "L"), which are not used to input the Japanese language using the roman letters.